Known technologies used for the deposition of metal conductors for applications in electronic components may be hampered by problems which may include limited deposition, non-uniformity of deposition, and/or non-adhesion of the conductor caused by surface layers on the material receiving the deposition. These problems may adversely impact the possible applications of metal deposition conductors. The possible applications of such conductors in electronic components include but are not limited to applications such as bonding pads, vias, wires, and other parts of integrated circuits, printed circuit boards, and other electronic applications. Surface layers leading to problems such as those noted above can, for example, include oxides or hydroxides resulting from exposure of the material receiving the deposition to air during transport from a prior process to the conductor deposition step, and/or by growth of the surface layer during immersion in solvents. In some cases, such as electrodeposition, such problem surface layers can be an unwanted byproduct of the deposition process itself. Such problem surface layers may often be non-uniform in coverage of the material receiving the deposition, and can have spatially differing densities. These undesirable surface layers can, for example, locally reduce the current available for electroplating of metal conductors, thus producing non-uniformities in the plated layer. Alternatively, surface layers can remain as contaminants between the plated layer and the material receiving the deposition after deposition, which may result in poor adhesion of the deposited film to the underlying surface.
In the case of conductors used for integrated circuit applications, copper for conductors is often desired to be deposited over a thin barrier layer of metal such as tungsten or a combination of titanium and tungsten that are deposited over integrated circuit wafers as one process step in a total manufacturing process flow. These thin barrier layers may be provided to adhere to an underlying integrated circuit structure, and adhere to the copper conductor, as well as being a barrier that protects the underlying integrated circuit components from copper contamination. In this case it is usual to deposit a thin “seed” layer of copper over the barrier metal layer by sputtering, chemical vapor deposition and/or other techniques, to allow uniform coverage, good adhesion between the barrier metal and the copper, and/or good electrical conduction paths to a subsequent electroplating bath that is used to deposit an even thicker copper layer for the final conductor structure. The copper seed deposition by sputtering or chemical vapor deposition steps may be preceded by a chemical or physical process step such as sputter etch to remove detrimental surface layers that have built up on the barrier metal layer during prior processing or air exposure. The electrochemical baths used for integrated circuit conductor deposition may be treated with substantial quantities of “additives”—chemicals specifically directed to removing surface layers that are present on the barrier metal layer or seed layer at the beginning of the electrodeposition step, or that occur during the deposition. The steps used to circumvent the detrimental effects of these surface layers in both initial “seed” deposition and in electrodeposition may be costly and/or time consuming.
There is, thus, a desire for improved conductor structures created by metal deposition and for improved methods for use in fabrication of electronic components. Electronic component applications may desire the deposition of high quality films of metals such as copper and the like. Such films may be enhanced in performance if they can be deposited uniformly and with surfaces that allow firm adhesion to the material on which they are deposited as well as to subsequently deposited layers. There also may be a desire for methods of metal deposition that could allow such materials to be handled more easily and to be processed in sequential steps without potential degradation, which can result in improved passivated conductors.